Solar energy thermodynamic motor



May 5, 1970 E. N. AVERY 3,509,715

' SOLAR-ENERGY THERMODYNAMIC MOTOR Original Filed Sept. 5, 1967 I a Imvcmon: EDWARD N. AVERY BY W ATTYS,

United States Patent 9 3,509,716 SOLAR ENERGY THERMODYNAMIC MOTOR EdwardN. Avery, 201 N. Grove St., Dunmore, Pa. 18512 Original applicationSept. 5, 1967, Ser. No. 665,618, now Patent No. 3,441,482, dated Apr.29, 1969. Divided and this application Jan. 14, 1969, Ser. No. 790,916

Int. Cl. F03g 3/00 US. Cl. 6010 5 Claims ABSTRACT OF THE DISCLOSURE Inapparatus for purification of impure water by humi dification usingsolar energy as a heat source, comprising: an impure water heating poolcovered by a material to prevent water evaporation therefrom whilepromoting absorption of solar energy into the heating pool, and a solarenergy still; a rotary thermodynamic motor to circulate the impure waterbetween the pool and the still. The mOtOr consists of a framework with aplurality of arcuate tanks positioned about the circumference.Diagonally opposite pairs of tanks are interconnected by conduits toeffect transfer of volatile liquid from the lower tank to the upper tankas a result of the heat energy supplied to the lower tanks by the poolwater. The transfer of the volatile liquid effects rotation of theframework.

This application is a division of my co-pending appli cation Ser. No.665,618 filed Sept. 5, 1967, now US. Pat. No. 3,441,482.

The present invention relates to a thermodynamic motor which is adaptedto use solar energy to effect rotation, and may have particularapplication in humidi fioation apparatus for recovering pure water fromimpure water.

Many attempts have been made for utilizing solar energy to drivemechanical apparatus, but none has been entirely satisfactory because ofthe difficulties in converting oscillating motion to rotary motion andin Obtaining efiicient operation thereof.

The present invention provides an improved thermodynamic motor in whichthe construction is relatively simple so as to Provide continuousrotation of the motor under an impetus gained from temperaturedifferentia arising from the effective use of solar energy.

More specifically the present invention provides for the utilization ofsolar energy to heat water in a pool and the use of the heated waterfrom the pool to provide a temperature differential between tanks atdiametrically opposite sides of a rotary framework to draw a volatileliquid from the lower tank to an upper tank, the transfer of the mass ofthe liquid creating an unbalance which rotates the framework, whichtherefore operates as a motor.

With the foregoing in mind, a primary object of the present invention isto provide an improved thermodynamic motor which converts solar energyinto rotational forces.

More specifically the present invention provides a motor of simplifiedconstruction which is rotated continuously by heat energy which providesa temperature differential between arcuate tanks at diametrically opposite sides of a rotary framework, and which effects transfer of avolatile liquid against the forces of gravity.

Other objects and a fuller understanding of the invention may be had byreferring to the following description and claims taken in conjunctionwith the accompanying drawings wherein:

FIG. 1 is a perspective view of a solar energy water purificationinstallation embodying a thermodynamic motor of the present invention;

FIG. 2 is an enlarged sectional view taken along the line 2-2 of FIG. 1showing the rotary thermodynamic motor to circulate the water throughthe canal; and

FIG. 3 is a sectional view taken along the line 33 of FIG. 2.

FIG. 1 illustrates a solar energy water purification installation havinga heating pool filled with saline or other impure water, a solar-energystill with an oscillating thermodynamic motor to promote watervaporization in the still, and a rotary thermodynamic motor to circulatethe water through a canal between the pool and the still.

As illustrated in FIG. 1, a still 15 is mounted in a canal 16 havingimpure water flowing therethrough from a pool 17. In the presentinstance, the canal is U-shaped with the still 15 mounted in the base ofthe U. A rotary thermodynamic motor 18 in accordance with the presentinvention circulates the water through the canal 16, in the inlet leg ofthe canal. A portion of the water circulating through the canal 16 isevaporated in the still and is condensed and collected in a reservoir,for example a tank 19 adjacent the still. The evaporation of the purewater from the canal raises the concentration of impurities in thereturn leg of the canal downstream of the still 15 and a sump 21 isprovided adjacent the return leg of the canal 16 to draw off the waterwith concentrated impurities from the canal. Means is provided to supplywater to the pool to make up for the evaporated water collected in thereservoir 19 and the water discharges. into the sump 21. In the presentinstance the water supply includes a settling basin 22 and a supply line23 having means 24 responsive to the water level in the basin tomaintain it full.

As set forth in my patent, the purification installation operateswithout substantial use of electricity or other generated power, and,when conditions permit, may generate useful power. Such generated powermay be stored for use in operating the installation when the climaticconditions are unfavorable, or may be used for other purposes asdesired. The primary source of power for operating the installation issolar energy and such other natural sources of power that are available.In the present instance, solar energy is used to elevate the temperatureof the water in the pool 17, preferably to a temperature substantiallyabove ambient temperature so that there is a substantial temperaturegradient between the ambient temperature and the watertemperature in thepool. The efiiciency of the pool is further enhanced if a source of hotwater is available, as for example from a hot spring. The illustratedinstallation is designed to employ shallow sources of water so as toreduce the amount of heating required in the pool 17.

The pool 17 is of a substantial area so as to have a large surfaceexposed to the radiant energy of the sun. To enhance the heating effectof the sun, a suitable cover means is provided over the pools surface.It has been found that an efiicient covering may be a continuous film ofdark oil or other suitable film-forming liquid having a density lessthan that of water and having heat-asorbing properties. The film-formingcharacteristic of the covering liquid film 25 prevents substantialevaporation of the water underlying the film, and the heat-absorbingcharacter of the film transmits the radiant solar energy to raise thetemperature ofthe water. Where the size of the pool permits, thecovering film may be a plastic material such as darkcolored polyethylenesheeting floated on the water and anchored at its edges to the innerwalls of the foundation through the inner walls of the pool. If a solidfilm of this character is employed, means is provided to collect rainwater from the surface thereof for transmission directly to thereservoir 1. If it is impractical to use a film as a heat-transmittingcover, floating cover elements such as barges may be used to transmitthe solar heat energy into the pool and retard evaporation therefrom.

In the present instance, the pool 17 is formed by a poured concretefoundation 26, but earthen foundations having water-impervious liningsmay be used. The foundation 26 is provided with a weir 27 to admitsurface water from the settling basin 22 into the pool 17, a barrier 28being provided to prevent the migration of the oil film from the pool 17into the settling basin. The weir is relatively shallow to insure thatwarmer surface water flows from the settling basin 22 into the pool. Thebarrier terminates at its lower end above the bottom of the weir 27 toafford flow of water from the basin 22 into. the ool 17. Since thesupply has means 24 to keep the basin 22 filled, the weir 27 maintainsthe pool 17 at the desired level.

As pointed out above, water from the pool 17 is circulated through thecanal 16 to supply the still 15, in accordance with the presentinvention the circulation being effected by a thermodynamic motor 18. Asshown in FIG. 2, the covering film 25 in the canal 16 is interrupted inthe area of the motor 18 for example by barriers 32 positioned upstreamand downstream respectively of the motor. As shown in FIGS. 2 and 3, themotor 18 comprises a rotary framework 33 having an axle 34 mounted forrotation in bearings 35 supported on A-frame supports 36. Apower-take-off 37 is connected to the axle 34 through a clutch device(not shown) to utilize excess power generated by the motor 18 when theoperating conditions permit it. The clutch is deenergized when theoperating conditions are substandard to eliminate the drag of thepower-take-off 37 from the axle.

In order to utilize the solar energy, the rotary framework 33 includes aseries of tanks 42 positioned about the circumference of the framework.In the present instance, the tanks are arcuate in form having acurvature corresponding to the radius of the framework and diagonallyopposite pairs of tanks are interconnected by conduits 43 extendingthrough the framework 33 and having open ends 41 adjacent the outerarcuate walls of each tank at the trailing end thereof, reckoned in thedirection of rotation of the framework. In the present instance, toincrease the efficiency of the motor, the tanks are coated with anabsorbent material as indicated at 44 and a spray mani fold 45 ispositioned adjacent the top of the rotary structure 33 to spray coolwater onto the surface of the tank.

In accordance with the invention, a volatile liquid 46 is contained inthe tanks to transform the solar energy into useful work. To this end,as shown in FIG. 2, the volume of the volatile liquid 46 within twointerconnected tanks is approximately equal to the volume in one of thetanks so as to leave a vapor space above the liquid approximately equalto the liquid volume.

In operation, the volatilization of the liquid in the lower tank of eachpair creates a vapor pressure within the lower tank which drives theliquid from the lower tank to the upper tank. The increased volume ofliquid in the upper tank partially fills the tank creating an unbalancewhich causes the framework 33 to rotate slowly counterclockwise as shownin FIG. 2. The volatilization of the liquid 46 in the lower tank isproduced by the elevated temperature of the water in the canal 16 which,in turn, raises the temperature of the liquid and increase its vaporpressure. In order to insure as warm a temperature as possible in theinlet leg of canal 16, the canal is relatively shallow at its inlet andgradually deepens towards the return end. In the top tank, the spraymanifold 45 cools the tank and the liquid therein to reduce its vaporpressure thereby further assisting the upward flow of liquid from thelower tank to the upper tank. As the framework 33 rotatescounterclockwise, the tank at the bottom rotates out of the water in thecanal 16 and the upper passes out of registry with the spray manifold45. There is still a considerable temperature differential between theupper and lower tanks due to the absorp tion of the cold water by thecoating on the upper tank and the warm water by the coating on the lowertank. This temperature differential maintains the upward flow of theliquid 46 for a limited period until the evaporative cooling of theabsorbed water eliminates the temperature differential. At this time,both tanks have been rotated past the horizontal level of the axle 34 sothat the ends 41 of the conduit 43 are above the level of the liquid inboth the upper and lower tanks thereby permitting vapor flow between thetwo tanks to equalize the pressures therein. Further rotation of theframework 33 rotates the downwardly moving tanks into the heated waterin the canal 16 and the upwardly moving tank into the registry with thespray manifold 44 thereby completing one-half cycle of the motor. Thusthe thermodynamic motor utilizes the pressure differentials produced bya volatile liquid to cause the liquid to fiow upwardly against gravitywhereupon the weight of the liquid at its elevated level produces therotational force to drive the framework,

The choice of a volatile liquid to be used in the tanks 42 dependsprimarily upon the vertical height and the temperature differencebetween the opposed tanks which are connected in pairs. Methylenechloride, or one of the fiuorinated hydrocarbons used as refrigerantssuch as dichloro-tetrafluoro-ethane, dichloro-difiuoro-methane ormonochloro-difluoro-rnethane might be used. Propane or even water may beused as a satisfactory volatile liquid under certain operatingconditions. Volatile liquids having substantial pressure differentialsfor small temperatture differences are preferred, and commercial tablesare readily available to assist in the selection of such liquids.

Depending upon the atmospheric conditionssurrounding the motor, theavailability of a cool water supply, and the operating characteristicsof the volatile liquid will determine the advisability of providing theabsorbent coating 44 on the tanks 42 and using the cool water psraymanifold 45. For example where the impurities in the pool and canalwater consist of a large concentration of chemical impurities, which maytend to accumulate in the absorbent coating 44 the coating should beeliminated. To provide for retention of the water on the surface of thetank, the surface may be etched or sandblasted to cause the tank surfaceto act in the nature of a wick to retain the water thereon.

The rotation of the motor 18 through the canal causes the water in thecanal 16 to flow or circulate therethrough. As illustrated, thecounterclockwise rotation of the rotors framework 33 produces left toright circulation of the water In the canal 16. To further enhance apumping effect of the motor 18, radial fins 48 are provided on the outerwalls of the tanks 42.

Pure water is recovered from the canal in the still 15 and istransferred to the reservoir 19 by means of a discharge tube mounted atthe right-hand side of the still as shown and described in detail in mypatent.

While a particular embodiment of the present invention has been hereinillustrated, it is not intended to limit the nvention to suchdisclosure, but changes and modifications may be made therein andthereto, as will be apparent to those skilled in the art.

I claim:

1. A thermodynamic motor comprising a support, an axle mounted forrotation on said support, at least two pairs of tanks, means mountingsaid tanks in spaced relationshtp on said axle, the tanks in each pairbeing in oppositcly disposed relationship about said axle, a transfertube interconnecting said tanks in said pair, a volatile liquidsubstantially filling at least one tank of each pair of tanks, and meansto effect a temperature differential between the tanks to cause the saidvolatile liquid in the lower tank at the bottom of its travel totransfer through said transfer tube to the upper tank to thereby shiftthe center of gravity of each of said pair of tanks and volatile liquidabout said axle to cause rotation thereof, said means to elfect atemperature differential comprising a body of heated water underlyingsaid axle and adapted to heat each tank at the bottom of its travel, anda spray manifold to spray water upon each of said tanks when it is inits upper position to cool the same and increase said temperaturedifferential and including an absorbent material on the outside surfaceof said tanks wherein said absorbent material receives water from saidspray manifold and said water evaporates from said material to furthercool said tank.

2. A thermodynamic motor as in claim 1, wherein each tank isarcuate-shaped and said transfer tube is connected to one end of saidtank, whereby said liquid enters said tank when in said upper positionand flows toward the other end of said tank to create a turning momentabout said axle.

3. A thermodynamic motor as in claim 1, including a power takeoff unitconnected to said axle to receive rotary power therefrom.

4. A motor according to claim 1, said body of heated References CitedUNITED STATES PATENTS 242,454 6/1881 Iske et al. 60'10 206,108 7/1878Hill et al 62 316 243,909 7/1881 Iske et al. 6010 250,265 10/1881 Landis6010 389,515 9/1888 Iske 60-10 3,362,186 1/1968 Patterson 62-316 CARROLLB. DORITY, JR., Primary Examiner US. Cl. X.R. 6025

